The invention relates to a volume management method for managing volumes in which the authority for operating an identical volume in a storage is regulated to avoid misoperations by users and to allow normal operation of the volume when a plurality of users manage the identical volume depending on the task of the users employing the volumes.
With an increasing amount of storage data, computer systems under corporate or other operation management include an increasing number of computer systems using high-capacity storage, and computer systems using a plurality of storages interconnected by SAN (Storage Area Network) which is a storage-dedicated network (primarily Fibre Channel) or IP (Internet Protocol) in which computers share a high capacity of data distributed among a plurality of storages. Moreover, for improved storage availability and other purposes, many storages have been provided with an increased number of, and enhanced capabilities. In the computer systems as described above, the increased amount of data to be managed complicates the operation management of storage, and also increases its cost. For this reason, a technique has been proposed for dividing a management range to divide users managing a plurality of storages in a storage network and high-capacity storages (e.g., Japanese Laid-Open Patent Application 2003-330622, hereinafter referred to as Patent Document 1).
In the technique disclosed in Patent Document 1, accessible volumes are assigned to users or hosts and their management authorities can be set up. According to Patent Document 1, the management range of the users can be clarified for each volume.
In another technique for enhanced capabilities of storage, in order to avoid the lowering of performance of an on-line process during a backup process, volumes in a storage are duplexed to replicate data for the on-line process. A server performing the backup process (backup server) treats the data of the replicated volume as a replication source to transfer the data to a backup destination (e.g., Japanese Laid-Open Patent Application 2002-41345, hereinafter referred to as Patent Document 2). This technique enables fast backup without burdening the on-line process.
These conventional methods have the following problems.
In a conventional technique as disclosed in Patent Document 2, in light of the volume replication technique for storage, the process of the backup server is triggered by the termination of replication. Thus a functionally different process is triggered by the change of status of the volume. However, continuous execution of these processes is assumed. No reference is made to any influence on replicated volumes that might be operated by another manager having a task other than backup, that is, to the manager's operation authority over the volumes. In a series of backup processes as disclosed in Patent Document 2, if another manager deleted any path connected with a backup server during the process of obtaining replicated volume data in a storage, the backup processes could not terminate successfully. In other words, without permission of the manager performing backup, the configuration of the volume may be arbitrarily changed by another manager. For this reason, a mechanism is required for managing authorities over volumes.
The conventional technique as disclosed in Patent Document 1 may sometimes address the above problems. However, division of the management range is a resource of the storage system including volumes. Operating a storage system involves various operations on the same volume. Such operations include, for example, setting of a path that defines a route for accessing data from a host, replication between volumes for data backup, and write protection on the volume for volume data protection. Since these operations are functionally different from the viewpoint of tasks, even a single volume may be managed by different managers for respective tasks. In this case, according to Patent Document 1, the same volume may be assigned to different managers. Therefore the same volume can be managed for each task by a different manager.
However, as disclosed in Patent Document 2, storage operations may change the status of volumes. In addition, some functions include storage operations assuming a plurality of settings for the storage operations. Such functions include, for example, replication between volumes described above. In this function, data written on a volume from a host is directly replicated to another volume within the storage, or on another storage, without the intervention of the host. However, the manager operating the replication between the volumes is only responsible for controlling the replication between the volumes and monitoring the status of volume replication on the assumption that the path has been set up. The path may be set up by another manager. This situation involves a plurality of instances of management in the same volume where, according to Patent Document 1, a management authority over paths is granted to a manager of path setup.
However, in the case of Patent Document 1, for example, even when a manager of volume replication manages the setting of replication, an authority for deleting paths of volumes is still granted to a manager of path setup. If the manager of path setup erroneously deletes a path, or creates a path to another host, then the setting of replication by the manager of volume replication becomes inoperative. More specifically, the change of path setup forces the manager of volume replication to manage volume replication under the condition that no data I/O is issued from the host, contrary to the assumption of the manager. Therefore the assumption of the manager of volume replication is violated.